Lauryn Hill -- Singer's Tax Problems Now $440,000 Worse

Lauryn Hill didn't just drop the ball on a $1.8 million tax bill from the federal government -- she also failed to pay $440,000 in taxes to the State of New Jersey ... so says the State of New Jersey.

A civil judgment was entered against Hill on June 14th by a Jersey court -- finding the Fugees singer is responsible for $446,386 in unpaid state taxes.

A week before the judgment came down, Hill was charged with failing to file FEDERAL tax returns in 2005, 2006, and 2007 ... a federal crime. She pled "guilty" and now faces 3 years in prison.

But lucky for Hill, the state tax situation hasn't become a criminal matter ... yet.

Hill is scheduled for sentencing in her federal tax case in November.

Calls to the singer's reps were not returned.